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This study aimed to conduct a finite element analysis-based seismic evaluation of an existing reinforced concrete (RC) building for a high seismic zone in northeast India. The building model was evaluated for demands using response spectrum analysis (RSA) per the latest Indian standards. Data on the condition of existing material strength, geometry, and initial design are collected on site. Here, a procedure has been introduced to evaluate the seismic demand and capacity of structural members, for prioritizing strengthening work. The focus of the study was on assessing the potential failure of columns, with an aim to evaluate a building's susceptibility to failure and collapse. This evaluation procedure was applied to an existing low-rise RC building in northeastern India that was originally designed for gravity loads. The building had significant plan irregularities and stiffness irregularities. As anticipated, it was observed that the building did not withstand seismic design action, and all the columns failed, while the beams failed partially. For various load combinations, the demand–capacity ratio, particularly in terms of axial load and biaxial bending moments of the columns, emerged as a critical force-based factor in evaluating the building's safety under combined forces. The obtained results were validated on site by visual inspection of structural longitudinal cracks under high combined (axial with biaxial moment) demand in columns. The case study identified the six most critical columns that might lead to building collapse and need immediate strengthening. This approach demonstrated its feasibility as a tool for assessing the seismic performance of existing low-rise RC buildings for prioritizing structural strengthening work. [ABSTRACT FROM AUTHOR]

The quality of yarn is largely determined by the properties of the fibers from which it is produced. There is a certain correlation between the properties of the fibers and the yarn. Toothed feeding cylinders with elastic casings act on the fiber tape according to the laws of mechanics. Thin shells are widely used in the design of elements in many branches of modern technology, particularly in mechanical engineering. In this feeding cylinder thin shells are installed, which helps to obtain high-quality yarn on rotor spinning machines. The calculated results of the feed cylinder with elastic casings in the feed area of rotor spinning machines are given. Each parameter is conditionally discussed according to the laws of dynamics and resistance of materials. [ABSTRACT FROM AUTHOR]

The underground granary with the prefabricated steel plate-concrete composite has presented the many advantages of energy conservation, loss reduction, and high grain quality, particularly for the requirements of low-carbon environmental protection and sustainable development. However, there are only limited reports on the vertical joints in the prefabricated steel plate-concrete composite wall. In this research, a new type of joint was proposed suitable for the precast steel plate-concrete composite wall in an underground granary. Four groups of steel plates were composed of the U-shaped, external/internal waterproof, and trapezoidal load-transfer steel plate. When the external waterproof steel plate of the new joint was used as the flange plate of the I-steel pile in the foundation pit supporting structure, the steel pile was assembled and connected with the precast block of the underground granary wall, further to realize the integrated construction of foundation pit and granary wall. Three types of precast steel plate-concrete composite specimens were designed to fabricate, including a new joint, non-trapezoidal load-transfer steel plate, and no joint. A two-point symmetrical loading flexural test was conducted to investigate the flexural performance of the precast steel plate-concrete composites in the elastic-plastic stage. An analysis was made on the failure modes, internal forces, and deformation behavior in each specimen under loads. The results indicated that there was a different development of crack and deformation in each specimen under the loading. Most cracks in the two specimens with joints appeared in the compression zone near the joints and the loading zone. By contrast, most cracks with non-joint appeared in the tension zone at the connection between the internal steel plate and concrete. There was the smallest deformation of the specimen with the new joint, and the largest that with no joint. The displacement and strain of each specimen increased with the increasing bending moment. Overall, the upper part of the specimen was in a compression state, whereas, the lower part was in a tension state. Specifically, the inflexibility of the new joint specimen increased significantly, where the flexural capacity increased by 15%, compared with the non-joint specimen. The stiffness and bearing capacity of prefabricated specimens were improved via the increasing concrete strength and the appropriate material parameters of the steel plate. Furthermore, the inflexibility of the new joint specimen increased remarkably, where the flexural capacity increased by 17%, and the yield load increased by 29%, indicating that the trapezoidal load-transfer steel plate effectively improved the joint performance, compared with the non-load-transfer steel plate joint. The mid-span tensile strains of the trapezoidal load-transfer and internal waterproof steel plate increased linearly with the increment of bending moment, where the tensile deformation was consistent, indicating that both of them played a tensile role in the new joint. The findings can provide a strong reference to design the flexural performance of prefabricated underground granaries and similar underground structures. [ABSTRACT FROM AUTHOR]

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Material strength under complex stress states is vital for structure design. This paper studied the strength and failure behaviour of 3D C/C composites under compression-shear coupled loads. Experiments were conducted using a modified anti-symmetric four-point bending (MAFPB) method and off-axis compression method. Two dominant failure modes were observed; 1) shear and 2) compression. Mode transitions under relatively low shear/compressive rations were also observed. Results show that the material exhibits significantly lower failure stress under shear-compressive load compared to compressive or shear strengths alone. Further analysis revealed that meso-scale geometry characteristic including tow crimps and interfacial cracks are the main inducements: (1) tow crimps lead to local bending moment and increase local shear stress, (2) matrix-tow cracks formed under shear load degrade the lateral support of axial tows, (3) matrix fibre splitting and local buckling within tows induced by compressive load further reduce the shear strength of axial tows. Failure stresses in off-axis tests are lower compared to those in MAFPB tests due to the existence of bi-axial compression. These findings show that shear failure is a weakness for the 3D C/C composite and can provide insights for further material design and structural strength analysis. [ABSTRACT FROM AUTHOR]

Abstract Following the experimental study and finite element (FE) model validation described in the companion paper, numerical parametric studies and the evaluation of design provisions for stainless steel channel sections under combined axial compressive load and minor axis bending moment are presented herein. The parametric studies were carried out to generate additional structural performance data over a wider range of cross-section aspect ratios and slendernesses, loading combinations and bending orientations. The test data and numerical results have been carefully analysed to develop a comprehensive understanding of the structural performance of stainless steel channel sections under combined compression and minor axis bending moment, and to assess the accuracy of the existing design provisions in Europe and North America. Comparisons of ultimate loads from the tests and FE simulations with the codified resistance predictions revealed that the current design standards typically under-estimate the capacity of stainless steel channel sections under combined compression and minor axis bending moment; this is attributed primarily to the neglect of material strain hardening and the employment of conservative interaction formulae. Improved design rules featuring more efficient interaction curves, anchored to more precise end points (i.e. cross-section resistances under pure compression and bending moment), are then proposed and presented. The new design proposals are shown to yield both more accurate and more consistent resistance predictions over the existing design provisions. Finally, statistical analyses are presented to confirm the reliability of the new design proposals according to EN 1990. Highlights • Parametric studies were carried out to generate further structural performance data. • Design provisions in EC3 and AISC were assessed against test and FE data. • New proposals were made, leading to substantial improvement in resistance prediction. • The reliability of the new proposals was confirmed according to EN 1990. [ABSTRACT FROM AUTHOR]

The ultimate strength of hull girder is the most important safety guarantee. For a long time, ultimate strength research of ship hull girder is usually under monotonically increasing bending moment. In fact, under extreme ocean wave conditions, the hull girder is more likely to withstand extreme cyclic-bending moments. Under which, the ultimate bearing capacity of the hull girder may be dominated by cyclic buckling failure, extreme low-cycle fatigue failure or the coupling of the two failure modes. In this paper, the ultimate strength and failure characteristics of five steel box girder models are studied under two different kinds of cyclic-bending moments (repeated sagging and alternate sagging/hogging). The two box girder models subjected to alternate sagging/hogging bending moments seem to be fractured due to the extremely low-cycle fatigue. The rest of the three models exposed to cyclic sagging bending moments are collapsed by cyclic buckling accompanying accumulated plastic deformation. The experiment shows that the extreme cyclic-bending moments will significantly reduce the ultimate bearing capacity and fatigue limit of ship girder, and lead to disaster. [ABSTRACT FROM AUTHOR]

Welded T-joints are commonly used in manufacturing of stiffened panels or crossbeams. However, welding of web-to-flange joint induces residual stresses and distortions resulting in significant challenges during both manufacturing and service. These issues can ultimately impact the structural performance, including fatigue and stability, and lifetime of the weldment. The purpose of current paper is determining the distribution and magnitude of manufacturing-induced longitudinal residual stresses in welded T-joints. Influence of hot rolling, thermal cutting, prestressing, welding, etc. are all included using the so-called contour method. Deformed surfaces are measured using coordinate measuring machine after wire electrical discharge machining of specimens. An inverse linear elastic finite element analysis is carried out for assessing residual stresses after data smoothing. Two-dimensional longitudinal residual stress patterns are evaluated in representative cross-sections clearly indicating high stress peaks near the welds, even exceeding yield strength of the base material. In addition, longitudinal membrane residual stresses are determined based on through-thickness stresses. In addition, a simplified residual stress model, satisfying the requirement for equilibrium of internal forces and bending moments, is developed for welded T-joints with double-sided fillet welds based on contour method results. [Display omitted] • A novel application of contour method is used for determining residual stresses. • Longitudinal residual stresses are assessed in welded T-joints. • Tensile residual stress peaks near the welds exceed yield strength of the material. • A simplified residual stress model is developed for welded structural steel T-joints. • Residual stress model satisfies equilibrium of internal forces and bending moments. [ABSTRACT FROM AUTHOR]

A model of a composite-to-steel hybrid balcony overhang is tested to find its strength and stiffness under imposed shear and bending loads. The configuration tested is representative of a solution being considered for the balconies of cruise ships, where the substitution of steel by composites aims at weight saving. The steel component is a channel type of structure made of two plates that serve as external supports of the sandwich plate. A finite element model is used to compare with the experimental results and to predict the critical regions of stress concentration. The results include load-deflection and load-strain curves with the maximum value of the shear and bending loads. The critical locations and failure loads have been investigated too. [ABSTRACT FROM AUTHOR]

A dent is one of the main structural damages that may affect ultimate strength. In this paper, the residual ultimate strength of dented metallic pipes subjected to a bending moment is quantitatively investigated. The numerical model is developed accounting for the variation of the dent length (ld), dent depth (dd), dent width (wd), dent rotation angle (θd) and dent location based on ABAQUS Python. The numerical model is validated by test results from a four-point bending test. Subsequently, a parametric investigation is performed on the effects of wave-type initial imperfection, D/t and dent geometrical parameters. It is found that both ld and dd have a significant effect on the residual ultimate strength of dented metallic pipes, while the effect of wd is slight. Finally, an empirical formula with respect to ld and dd has been proposed for the prediction of bending moment, which can be deployed for practical purposes. [ABSTRACT FROM AUTHOR]

As technology advance in 3D printing, octet lattice materials can be made with a wide range of strut aspect ratios. It is essential to develop a satisfying theoretical model for large aspect ratio ranges. In this paper, an analytical model considering material overlapping effect in strut joint, bend and shear has been derived to predict the effect compressive stiffness and strength of the octet lattice materials with cylindrical struts. The models have been validated by FE simulations and experiments. These results demonstrate that the relative compressive stiffness and strength not only depend on the relative density, but also relate to the effect of strut joint, bend and shear. The material overlapping effect in strut joint and the coupling effect between the shearing force and the bending moment will raise the relative compressive stiffness and strength. [ABSTRACT FROM AUTHOR]

This article shows how bending and torsional moments in three-dimensional frames can be represented via a discontinuous Maxwell-Rankine stress function. The associated Rankine reciprocal contains polygonal faces whose areas represent forces. These faces are orthogonal to the member forces (which may include shear forces) and need not be orthogonal to the beams. [ABSTRACT FROM AUTHOR]

Based on realistic modeling of 44 bridges in national bridge inventory using its actual layout and dimensions, a theoretical framework is defined to calculate the tolerable differential settlement limits based on the over-bending moment or over-shear force generated by settlements and the moment or shear capacity of the bridge. First, the derived over-bending moment or over-shear force is validated through literature results. Second, the differential settlement limits of bridges are derived from the bridge strength capacities. Finally, based on the established differential settlement limits, the relationship of bridge differential settlement limits with its span length, number of spans, bridge skew, and the bridge type is discussed and compared with American Association of State Highway and Transportation Officials specification (2010). A statistics-based differential settlement limit criterion is also suggested for steel and pre-stressed concrete bridges and compared with the field survey results. From the research outcomes, it is concluded that extra caution is needed when implementing the 0.4% differential settlement limits of bridge foundations in American Association of State Highway and Transportation Officials. [ABSTRACT FROM AUTHOR]

Along with proposing any innovative structural element for design purposes it is necessary to understand its behaviour under combined structural actions. This paper includes experimental, numerical and analytical investigations on an innovative type of hybrid fabricated section consisting of high strength tubes and mild steel plates under the effect of axial compression and bending moment interaction. As a special case of interactive condition, pure bending performance of the hybrid fabricated member is examined with focus on the local failure mechanisms and analytical expressions are proposed to predict the moment resisting capacities. Furthermore, compression-bending interaction curves are obtained from plastic analysis of hybrid hollow sections and compared to relevant standard formulations. The compression-bending curves obtained for various ratios of tube cross-section and strength to that of plate show that a linear interaction formula is applicable to predicting the plastic interaction behaviour of sections with high ratios while sections with lower ratios are closely predicted by a bilinear interaction formula. This paper also includes beam-column tests accommodating combined effects of compression, bending and also shear. Employing the developed and validated finite element model, a parametric study is conducted on the effect of section geometry and material on the axial-lateral interaction of beam-columns. Referring to the member interaction results, reaching an optimum interactive performance stands on the design of both geometry and material of plate and tube elements. [ABSTRACT FROM AUTHOR]

Due to their high fatigue life, specific strength and specific stiffness in comparison with steel, carbon-fibre reinforced polymer (CFRP) cables have attracted the infrastructure industry interest in recent years, primarily for use as structural tendons. Particularly the oil and gas industry showed interest for application in offshore platform anchorage systems, because of their exceptional corrosion and creep/relaxation behaviour. In such applications, the cables need to be tensioned in service and to be bent around relatively small-diameter spools for transportation and maintenance. Therefore, their tensile and bending behaviour is a subject of great concern. The aim of this work was to perform a test program on 1 × 19 CFRP cables in two different situations: tensile loading and four-point bending loading. Finite element models were developed to simulate both conditions, including frictional contact between the cable wires. A simplified analytical model was also used to predict the cable behaviour in tension. Numerical predictions were compared to experimental data showing relatively good accuracy, unlike the verified analytical model. CFRP cables presented outstanding tensile behaviour, but bending over small radius spools could not reach the performance of steel wire ropes. Furthermore, simulation could only fairly predict bending below strains of ±1,000 µe for the external rods, beyond which the cable presented highly non-linear behaviour that could not be simulated by the numerical model. [ABSTRACT FROM AUTHOR]

During dual-casing sidetracking, it is found that the hardness values of productive casing, cement sheath, protective casing and rock stratum are different from each other, and the contact surfaces between the drill bit and the whipstock, productive casing, cement sheath, protective casing and rock stratum are also different. In consideration of the actual conditions of contact between the drill bit and the whipstock, productive casing, cement sheath, protective casing and rock stratum During dual-casing sidetracking, we built a mathematic model for describing the moment of dual-casing sidetracking drill bit, and then, on the basis of field engineering cases, obtained the curves by using the MATLAB software for describing the relations between the moments and horizontal moving distances of drill bit under three different working conditions. We thereupon discussed, in the view of metal cutting mechanics, the cutting force and torque of drill bit during the sidetracking, verified the strength of sidetracking drill bit, and further provided the technical suggestions for avoiding the bit jamming and breaking accidents During dual-casing sidetracking. Although the mechanics analysis model of the window drill does not fully explain the bit damage seen in the field, but the related analyses and calculations can be used as references for determining the parameters for both design and drilling of dual-casing sidetracking drill bit. [ABSTRACT FROM AUTHOR]

This paper presents a method for numerical analysis of the effectiveness of using the engineered cementitious composites with polyvinyl alcohol fibers for concrete cover repairs. The numerical analysis utilizes a nonlinear three-dimensional Rigid-Body-Spring Model which has strong capabilities to assess the crack width and crack patterns in the concrete structures. The applicability of the analysis is demonstrated on a reinforced concrete frame corner which is subjected to both the action of the positive and the negative bending moment. The effectiveness of the added overlays is shown in a comparison of the frame corner with and without the engineer cementitious composite overlays. The added overlays reduce the crack width and thus extend durability of reinforced concrete structures. [ABSTRACT FROM AUTHOR]

Repair welding for recovery from local damage of a rail head surface is known to cause high residual stress and can accelerate fatigue in the rail. This study examines repair-welded rails by applying experimental and numerical approaches. In the former approach, two newly manufactured rail specimens and four repair-welded rail specimens with two different weld depths were prepared, and their residual stresses were measured with a sectioning method. In the latter approach, a finite element repair welding simulation model was developed that adopted a prescribed temperature method with a moving block as an input heat source, and the thermal strain caused by the volume change due to solid-state phase transformation was considered. Overall, the residual stresses correlated well between the experimental and numerical approaches. The measured high compressive residual stress of −290 MPa seems to be beneficial to prevent a crack initiation in the rail surface. [ABSTRACT FROM AUTHOR]

In the study herein presented, the influence of nanoparticles additions on the structural behavior of reinforced concrete beams is analyzed, in terms of both shear strength and bending moment capacity. For this purpose, concrete mixtures with additions of either silica nanoparticles (nano-SiO 2 ) or aluminum nanoparticles (nano-Al 2 O 3 ) were produced. An experimental program was organized in two different sets: i) eight beams tested until shear failure was reached; and ii) eight beams tested until failure in bending was observed. These beams were produced with eight distinct concrete mixtures, with and without nanoparticles, and with and without steel fibers. Based on the data recorded, the following was analyzed: the force-displacement curve, the maximum strength in shear and in bending, the average curvature at critical cross-sections, the bending stiffness, the cracking pattern, and the failure type. It was concluded that the addition of nanoparticles, mainly nano-Al 2 O 3 , to the concrete mixtures can lead to a strength increase, both in shear and in bending. It was also concluded that the interaction between the nanoparticles and the steel fibers can have a negative effect on the beams strength. [ABSTRACT FROM AUTHOR]

A methodology for reliability assessment for hull girder ultimate strength of FPSOs is presented in the paper. The hull girder ultimate strength of a FPSO is calculated by a progressive collapse analysis using the Smith method. Uncertainty of still-water bending moment (SWBM) is evaluated based on the loading conditions from FPSO operational manuals. A stochastic model of the extreme value of vertical wave-induced bending moment (VWBM) is developed in accordance with the extreme value theories based on the long-term distribution of VWBM. A first-order reliability method coupled with finite difference methods is proposed for reliability estimate dealing with the complicated implicit limit state function for hull girder ultimate strength assessment. Reliability assessments for four FPSOs are performed to demonstrate the capability of the methodology developed. The effects of the return period of the extreme value of VWBM, environmental severity factor and corrosion effects on hull girder reliability are investigated. A sensitivity analysis for each random variable is also conducted. [ABSTRACT FROM AUTHOR]

This paper reports the second part of the study on the structural behaviour of stainless steel circular hollow sections subjected to combined axial load and bending moment. A series of numerical parametric studies is presented, using the validated finite element (FE) models from the companion paper, with the aim of generating further structural performance data over a wider range of stainless steel grades, cross-section slendernesses and combinations of loading. The considered parameters include the outer cross-section diameter, the ratio of outer cross-section diameter to thickness and the initial loading eccentricity. Both the experimentally and numerically derived section capacities were compared with the strength predictions determined from the current European code, the American specification and the Australian/New Zealand standard, allowing the applicability of each codified method to be assessed. The comparisons revealed that the current design standards generally result in unduly conservative and scattered strength predictions for stainless steel circular hollow sections under combined loading, which can be primarily attributed to the neglect of strain hardening in the determination of cross-section resistances and to the use of linear interaction formulae. To overcome these shortcomings, improved design rules are proposed through extension of the deformation-based continuous strength method (CSM) to the case of circular hollow sections subjected to combined loading. Comparisons between the proposals and the test and FE results indicate a high level of accuracy and consistency in the predictions. The reliability of the proposed approach was confirmed by means of statistical analyses according to EN 1990. [ABSTRACT FROM AUTHOR]

A comprehensive experimental and numerical investigation into the structural performance of stainless steel circular hollow sections (CHS) under combined compression and bending moment has been performed and is fully reported in the present paper and its companion paper. The experimental programme employed four CHS sizes made of austenitic stainless steel, and included material tensile coupon tests, four stub column tests and twenty combined loading tests. The initial loading eccentricities for the combined loading tests were varied to provide a wide range of bending moment-to-axial load ratios. In conjunction with the testing programme, a numerical modelling programme was performed to simulate the experiments. The developed FE models were shown to be capable of replicating the key test results, full experimental curves including the post-ultimate range and deformed failure modes. Upon validation of the FE models, a series of parametric studies were conducted in the companion paper, aiming at extending the current test data pool over a range of cross-section sizes and combinations of loading. The experimental data, together with the generated parametric study results, were analysed and employed to evaluate the applicability of the codified provisions given in the European code, American specification and Australia/New Zealand standard for design of CHS under combined loading. Improved design rules were also sought through extension of the deformation-based continuous strength method (CSM) to the case of stainless steel CHS under combined loading. [ABSTRACT FROM AUTHOR]

We consider plane waves in the linear elastic reduced Cosserat continuum, a medium where point-bodies have independent rotational and translational degrees of freedom, but couple stresses are zero, since the medium does not react to the gradient of turn. We consider the case of the simplest anisotropic coupling between volumetric and vortex-rotational strain, determined by a certain constant vector n. All other tensors are isotropic. For almost all directions of wave propagation there exists a frequency band gap below a specific frequency ω0, i.e. the medium is a single negative acoustic metamaterial in a certain domain of frequencies. The longitudinal (in the sense of translations) wave, propagating along this vector, has a behaviour similar to the shear-rotational wave in the isotropic case (high dispersion in the domain close to ω0 and the band gap below it). Most of waves are mixed (neither longitudinal nor transversal), and the relation between amplitude components is frequency dependent. The wave, propagating in the direction perpendicular to n, has no forbidden band, but it is mixed (the relation of components depends on frequency). We hope that this or a similar model can be applied for understanding wave propagation in granular media. [ABSTRACT FROM AUTHOR]

Shakedown occurs when a structure responds steadily under cyclic loadings within appropriate limits after one or a few cycles of loading. This study proposes a new method for assessing the shakedown limit state associated with the breakage of a ship's hull girder, considering the buckling effects seen under the cyclic hull girder actions of hogging and sagging bending. The method is applied to a Suezmax-class double-hull oil tanker as an example. The shakedown limit state of the ship under cyclic hull girder actions is analysed, and the results are compared with the ultimate hull girder strength of the ship under monotonically applied hull girder loads. It is concluded that a ship's hull under cyclic actions of vertical bending can collapse, with a shakedown failure even if the vertical bending moments applied are smaller than the ultimate hull girder strength determined under monotonically applied hull girder loads. The method and insights developed will be useful for assessing hull girder breakage subject to cyclic hull girder bending moments. [ABSTRACT FROM AUTHOR]

In the present paper, a two-dimensional solid consisting of a linear elastic isotropic material, for which the deformation energy depends on the second gradient of the displacement, is considered. The strain energy is demonstrated to depend on 6 constitutive parameters: the 2 Lamé constants ( $${\lambda}$$ and $${\mu}$$ ) and 4 more parameters (instead of 5 as it is in the 3 D-case). Analytical solutions for classical problems such as heavy sheet, bending and flexure are provided. The idea is very simple: The solutions of the corresponding problem of first gradient classical case are imposed, and the corresponding forces, double forces and wedge forces are found. On the basis of such solutions, a method is outlined, which is able to identify the six constitutive parameters. Ideal (or Gedanken) experiments are designed in order to write equations having as unknowns the six constants and as known terms the values of suitable experimental measurements. [ABSTRACT FROM AUTHOR]

Although multi-span cable stayed bridge is a new and elegant structure, its structural characteristics are not fully understood. The static and seismic behaviors of a multi-span cable stayed bridge with three different types of tower, RC and steel/concrete hybrid and steel tower, were studied. The steel/concrete hybrid tower consists of a sandwich type double steel box section filled with concrete, the RC tower has a rectangular hollow section and the steel tower has a steel box section. First, static analysis is conducted with different live load patterns. Size and material strength assumed, which was validated by the limit states design. Second, elastic and plastic seismic analysis is conducted for the three towers. Medium strong and ultra-strong earthquakes according to Japanese Seismic Codes for Highway Bridges were adopted. Dynamic responses were obtained and compared. In summary, RC and hybrid tower showed very good static features and energy dissipating behavior during earthquakes. Steel tower had the largest displacement but the least bending moment. [ABSTRACT FROM AUTHOR]

Subsea pipelines used for oil and gas production in deepwater are exposed to harsh environment involving corrosion, high internal pressure, high temperature, and bending moment. Failure of subsea pipelines can cause serious problems, including oil/gas spill, hydrocarbon explosion and fires, production downtime, and maintenance and repair. Hence, it is of paramount importance to prevent failure of subsea pipelines. The aim of the present study is to investigate the residual strength characteristics of corroded subsea pipelines under combined internal pressure and bending moment. ANSYS non-linear finite element method was applied to examine the residual strength characteristics of subsea pipelines by varying the corrosion damage and the loading ratio of internal pressure and bending moment, where the size of the corrosion damage was also varied. The ultimate strength interaction relationships of subsea pipelines between the internal pressure and bending moment with various corrosion damages were also developed. Finally, the insights and conclusions of the present study were summarised. [ABSTRACT FROM PUBLISHER]

In this paper, the structural strength and stability of cold-formed steel lipped channel beam-columns under bi-axial moments and axial force are experimentally investigated. The results are employed to evaluate the reliability of the current North American cold-formed steel design standard, AISI-S100-12, for predicting the strength of beam-columns, by both the effective width method (EWM) and the direct strength method (DSM). Fifty-five 600S137-54 (AISI-S200-12 nomenclature) lipped channel beam-column sections with three different lengths: 305 mm (short), 610 mm (intermediate), and 1219 mm (long) are tested under combined bi-axial bending moments and axial force to characterize the failure modes and the member capacity. A loading rig specifically designed to apply eccentric axial load, in order to provide bi-axial bending and compression to the specimens, was developed and detailed herein. The experimental observations reveal that the failure modes are highly dependent on the stress distribution applied on the cross-section by the combined actions. The results show a considerable potential for improvement in current specification approaches which utilize a simple interaction equation, as this typically results in conservative strength predictions. The potential for further improvement of the current specification for predicting the strength of cold-formed steel beam-columns is discussed. [ABSTRACT FROM AUTHOR]

The structural response of typical, gable-end, low roof pitch industrial buildings, in a windstorm is dependent on the wind loads used in the design of cladding and the portal frame structure. Critical, structural wind load effects derived from wind loads measured on a wind tunnel model show that standards such as AS/NZS 1170.2 can produce unconservative design load effects on the heavily loaded fi rst internal frame. This paper forms part of wider study that assesses the vulnerability of hot rolled steel, industrial buildings to wind loads. The knee and ridge bending moments and horizontal and vertical reactions at the base of the frame are the critical load effects that are used in the design of structural members and connections of these types of buildings. This study found that some of these load effects based on external pressures are under-estimated by about 30%, when the building is located in a suburban environment. A dominant windward wall opening can effectively double the design load effects, thus signifi cantly increasing the vulnerability, especially if this scenario has not been considered by the designer. [ABSTRACT FROM AUTHOR]

Abstract: The manufacture of bent tubes made of high-strength materials requires high bending loads, which lead to large springback and eventually distortion of the cross-section. The incremental tube forming process allows significant reduction of the bending moment. This is achieved by combining the continuous bending process with an incremental tube spinning process. The paper describes an analytical model to predict the bending moment reduction as a function of the superposed spinning process parameters. Experimental results are provided to validate the theoretical results. This model allows the design and optimization of the incremental tube forming process with low springback. [Copyright &y& Elsevier]

Abstract: Summarized herein is a study that explored single span, horizontally curved, plate girders having a yield stress of 50ksi (345MPa) to investigate their flexural behavior as a function of the position of a single longitudinal stiffener at various locations along the depth of the web. The studies were conducted using ABAQUS [1] with the girder cross-sections under high vertical bending moment and low shear. As a result of these studies, recommendations are made for positioning longitudinal stiffeners on horizontally curved webs that complement existing criteria for straight plate girders in bending. The study shows that, for the high flexure situations and girder specimens that were examined: (1) the optimal position for longitudinal stiffeners on a horizontally curved web does not appear to differ appreciably from that for a straight web as recommended in the AASHTO LRFD Bridge Design Specifications [2]; and (2) horizontal curvature can contribute to enhancing web stability, and, in certain instances, curvature may mitigate the need to use longitudinal stiffeners to help increase cross-section flexural strength. [Copyright &y& Elsevier]

Abstract: This work deals with the evaluation of the ultimate bending moment of a severely corroded box girder subjected to uniform vertical bending moment through a series of nonlinear finite element analysis. Two models of corrosion degradation have been adopted, one is an average general corrosion thickness reduction, and the other is the real thickness of the corroded plates. New stress–strain relations have been developed to account for the effect of corrosion on the flexural rigidity. To validate the new developed stress–strain relationships, a comparison between the finite element analysis results using the existing stress–strain models, the newly developed ones and the experimental test results of a severely corroded box girder have been conducted. The comparison showed a good agreement and supported the choice of the newly developed stress–strain relationships of corroded structures. [Copyright &y& Elsevier]

Gasketed bolted flanged pipe joints are widely used in industrial applications and are prone to failure in terms of sealing and strength. In this paper, flange bending stress, flange rotation, bolt bending, stress variation at gasket and centring ring of the gasketed flange joints are analysed during bolt up and internal pressure loading. Three pressure classes 150# (12-600 mm (0.5-24 in.)), 900# (12-600 mm (0.5-24 in.)) and 2500# (12-300 mm (0.5-12 in.)) were employed for comparison of results. For better joint strength and sealing, the bolts were prestressed to 50% of their yield strength during bolt-up and 20% surface yielding is allowed at the hub-flange fillet. In addition, raised face on the flange faces are machined to control flange rotation and bolt bending and achieve required gasket seating stress. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigated the bending strength of girth-welded stainless steel circular hollow sections by numerical method. At first, finite element simulation of girth welding process was carried out to obtain the weld-induced residual stresses and deformations employing sequentially coupled three-dimensional thermo-mechanical finite element formulation. Then, nonlinear finite element analysis in which the moment versus end-rotation response, the ultimate moment resistance and the failure mode of the girth-welded circular hollow sections under pure bending were explored incorporating the residual stresses and depressions along with the initial global geometric imperfections was performed. Feasibility of adopting the current codified provisions (Eurocode 3) for stainless steel circular hollow sections in bending as the cross-section slenderness limit for girth-welded stainless steel circular hollow section flexural members was also examined. Results showed that the flexural behavior of girth-welded stainless steel circular hollow sections always involves local buckling near the girth weld on the compression side, which significantly affects the moment versus end-rotation behavior. Moreover, the results demonstrated that the Class 3 slenderness limit of 280 from Eurocode 3 for stainless steel circular hollow sections in flexure may be applied to girth-welded stainless steel circular hollow sections subjected to bending. [Copyright &y& Elsevier]

Highlights: [•] An envelope failure law of the GFRP/concrete interface was defined based on the Mohr–Coulomb criterion. [•] Properties of the envelope failure law were quantified by means of a shear test campaign. [•] T-beams externally reinforced with GFRP plates were submitted to bending tests of 4 points. [•] The T-beams and the shear tests were modulated with a 3D FE code. [•] Models with rigid and gap interfaces combined with the rotated and fixed crack approaches were studied. [Copyright &y& Elsevier]

Abstract: The springback law and springback prediction are always the difficulties in the field of profile stretch–bending processing. Because of the urgent demand for stretch–bending flexible manufacturing, the study on stretch–bending springback aiming at the profile with a given cross-section cannot meet the requirement. In this paper, the profile with any cross-section was taken as the study object. In the loading method of pretension and moment, the mechanical models of profile stretch–bending were established based on the classical elastic–plastic theory and the characteristic of strain superposition. Different distribution states of stress and strain on cross-section were discussed, and the method of discriminating different distribution states was given. The universal analytic method of solving the plane stretch–bending springback of profile with any cross-section was obtained. Two kinds of typical profiles with U-section and rectangular section were taken as examples to verify the theoretical analysis. The stretch–bending springback laws obtained by theoretical analysis, numerical research and experimental research agreed well. This study provides a theoretical foundation for stretch–bending flexible manufacturing and has certain theoretical and engineering guidance value. [Copyright &y& Elsevier]

Abstract: The rotational capacity of I-girders in the negative bending moment region is a crucial design parameter, since a large negative bending moment occurs near bridge piers where plastic hinges are first formed. Thus, the continuous girders on the intermediate supports must have sufficient rotational capacity (or flexural ductility) to redistribute the negative bending moment into an adjacent positive bending moment region to ensure ductile behavior of the girder. Furthermore, the rotational capacity of I-girders built up with high strength steel plates is usually smaller than that of I-girders built up with normal strength steel plates; the rotational capacity therefore needs to be improved. High strength steel with yield stress of 690MPa was used for this study. A theoretical model to predict the rotational capacity of the I-girder with high strength steel was proposed based on the analytical model of a flexural curvature distribution diagram. The theoretical model was verified through a series of tests and parametric studies. Further, the optimum arrangement of bracing points to maximize the rotational capacity was derived, and the proposed optimum bracing point was successfully verified. [Copyright &y& Elsevier]

Abstract: The stress distributions at the interfaces in the scarf adhesive joints under static bending moments were analyzed using two-dimensional and three-dimensional finite element (FEM) calculations. The effects of the scarf angle, adhesive Young's modulus and the adhesive thickness on the interface stress distribution were examined. It was found that the singular stress at the edges of the interfaces decreased as the adhesive Young's modulus increased and the adhesive thickness decreased. The singular stress at the edges of the interfaces obtained from the 3-D was larger than that from the 2-D FEM. The joint strength was also predicted using the elasto-plastic 3-D FEM calculations. For verification of the FEM calculation results, the strains in the adherends and the joint strengths were measured. The measured results of the strains and the joint strengths were fairly consistent with the results obtained from the 3-D FEM calculations and indicated that the rupture bending moment (joint strength) was the maximum when the scarf angle was around 60°. [Copyright &y& Elsevier]

Abstract: This paper presents the results of an investigation of the effect of lateral pressure on the progressive hull collapse behaviour of a double-hull oil tanker subject to vertical bending moments in both the sagging and hogging conditions. As an illustrative example, a Suezmax-class double-hull oil tanker designed by the Common Structural Rules (CSR) method is considered. The ANSYS nonlinear finite element method (NLFEM) is employed for the progressive hull collapse analysis. The effects of lateral pressure – static (anchored condition) and dynamic (operating condition) – are investigated in both the full-load and ballast conditions. To check the accuracy of ultimate hull girder strength analysis methods, Dow''s test hull is also applied together with Suezmax class oil tanker under conditions of vertical bending moment but without lateral pressure loads. In this regards, the NLFEM method is compared with ALPS/HULL intelligent supersize finite element method (ISFEM) programs and International Association of Classification Societies (IACS) CSR method, which applies the idealized structural unit method (ISUM) (also called the Smith method). The important insights developed from the present study are documented. [Copyright &y& Elsevier]

Abstract: Fibre reinforced composites are extensively used in applications that exploit their high strength to weight and modulus to weight ratios. Structures made of composites can be subjected to random structural excitation that spans a significant fraction of the audible frequency range, thus exciting a large number of modes. The concept of modal density is employed when such excitation is present and it is a critical parameter for the high frequency tool, statistical energy analysis. In this paper an analytic expression, independent of boundary conditions, is derived for the modal density of fibre reinforced composite beams coupled in bending and torsion. The variation of the modal density with fibre orientation for a unidirectional fibre reinforced composite is investigated and it is seen that there exists in every frequency band an orientation that corresponds to a minimum modal density. The additive property of the modal density for discontinuous composite beam systems is also verified. [Copyright &y& Elsevier]

Abstract: The objective of this paper is to analyse the ultimate strength of ageing ship structures based on experimental and numerical assessments. Three experimental ultimate strength tests have been carried out on box girders under vertical bending moment and several effects have been detected due to corrosion. Extensive nonlinear finite element analyses have been performed to compare the numerical and experimental results. The ultimate bending moment of corroded box girders has been compared with existing formulas. A relationship to calculate the equivalent tangent modulus as a function of the total reduction of the cross-sectional area due to corrosion degradation has been proposed. A new stress–strain relationship has been developed, taking into account the residual stresses and the corrosion effect, which may be directly used as a master stress–strain curve for a non-linear finite element analysis. [Copyright &y& Elsevier]

Abstract: Reinforced concrete (RC) beams strengthened in flexure by externally bonding fibre reinforced polymer (FRP) or steel plate on their tension face are susceptible to premature plate end debonding failures. Safe design of such a strengthened RC beam demands a reliable and predictive debonding strength model. There are two special cases of plate end debonding failures: flexural debonding for cases when the plate terminates within a constant bending moment region (CMR), and shear debonding for the case when the plate terminates where the shear force is large but the bending moment is minimal. A general plate end debonding case is usually considered as an interaction between these two special cases. This paper is concerned with flexural debonding. A brief review of existing models is presented before the plate end interfacial stresses are examined. Three new models with different levels of accuracy are then developed: a closed-form theoretical model based on a simplified interfacial fracture mechanics analysis; a semi-empirical model; and a wholly empirical model. These three models together with two existing models are assessed against a carefully constructed test database containing 67 test data from an extensive literature survey. [Copyright &y& Elsevier]

Abstract: In this paper a comparison between the analytical expressions for the prediction of the load carrying capacity of strengthened reinforced concrete (RC) columns with steel angles and strips is made. Expressions examined consider: the strength contribution due to the confinement effects induced by transverse strips; the composite action due to steel angles and unconfined concrete core; the strength contribution due to the composite actions of angles and concrete core taking into account that steel angles are subjected to axial force and bending moment and concrete core is confined by transverse strips. Design rules given by recent codes for the design of the strengthened columns are given. Therefore, results here generated, in terms of load carrying capacity, were compared with good agreement with experimental data available in the literature and with those obtained by using the existing models. [Copyright &y& Elsevier]

Abstract: Steel caging is an effective, economical, easily applied and widely used method of strengthening RC columns. Based on the results of two experimental studies, this paper proposes the finite element modelling of RC columns strengthened by a steel cage under axial loads and bending moments. The FE models were used to obtain the N-M diagrams of experimental cases in which a study was made of the improved resistance of RC columns strengthened with this type of strengthening technique. The paper also includes a comparison of different methods of connecting the cage around the beam–column joint and a parametric study to observe the influence of diverse parameters on the behaviour of the strengthened column, including: angle dimensions, number of strips, the yield stress of the steel used in the strengthening, the dimensions of the capitals at both ends of the column, concrete strength and the characteristics of the reinforcement used in the columns. Finally, the results of the various tests (experimental and numerical) described in the paper are used to be compared with three design proposals and the goodness of fit of each one is analysed. [Copyright &y& Elsevier]

In order to create a systematic design method for out of-plane stability of steel arch under the combination of uniform compression and bending, the out-of-plane ultimate strength of circular arch under bending moment is required to be investigated at first. By considering the factors such as arch section types, initial geometric inperfection, residual stresses, rise-to-span ratio, support conditions and end moment ratio, this paper presented design principles for out-of-plane strength of circular arches under bending moment. Firstly, arches under uniform positive bending were studied and stability design curves with normalized arch slenderness for welded I-section, welded box section and hot-rolled pipe section were proposed. Then for arches under non-uniform bending with end moment, two methods of modified normalized slenderness and moment modified coefficient for calculation of the out-of-plane ultimate strength were established, which can be applied in the formulation of design method for arches under the combination of compression and bending. It shows that the stability curve of circular arches under uniform positive bending is similar to that of straight beams. Modified normalized slenderness or moment modified coefficient should be introduced to take account of the effects of moment gradient and negative moment. The results of ultimate strength calculated by the two methods proposed are close to those of FEA. [ABSTRACT FROM AUTHOR]

Abstract: In this research, 18 laced built-up columns with various geometric specifications were analyzed under different levels of axial load and cyclic lateral load using the finite element method. This research was performed as a continuation of the experimental investigation on the cyclic behavior of the laced columns. This study evaluated the effects of column''s geometrical parameters and various levels of axial loads on the cyclic behavior of laced columns. A compression of the results shows that there is generally good agreement between the experimental and analytical results. The analytical results showed that as the axial load increased, the ductility of the laced columns decreased significantly. Further, at high levels of axial load (i.e., loads higher than 50% of the columns'' compressive capacity), ductility was very poor. It was found that during lateral loading there is a bending moment in addition to the axial force in the lacing bars and the main chords, which affects the columns'' behavior. The slenderness ratio of the main chords between the connecters and the shape of the cross-section of the lacing bars (i.e., bending strength of the lacing bars) are the main geometrical parameters affecting the laced columns'' ductility. [Copyright &y& Elsevier]

Abstract: A new methodology is presented for the ultimate strength and moment–curvature analysis of arbitrary composite sections under biaxial bending and axial load. The definition of section geometry and material properties can be unconditionally complex, based on an object-oriented implementation. Stress integration is performed using a Green path integral, with an adaptive strain-mapped Gaussian sampling. Derivative-free solution strategies for the calculation of incremental and ultimate response are applied. Results are presented in the form of moment–curvature curves, ultimate strength interaction curves and 3D failure surfaces. The performance of the methodology is demonstrated through various case studies, comparisons and benchmarks. [Copyright &y& Elsevier]

Abstract: The plastic criteria for the verification of steel cross-sections resistance are usually based on some basic hypotheses such as the development of plastic hinges, which depend on the interaction between the internal forces and the cross-section shape; therefore, specific equations are required for each type of cross-section. This paper presents new alternative interaction criteria for the analysis of steel I-sections subjected to an axial force and biaxial bending moments, at the elastic or the plastic limit states (as long as buckling phenomena are not involved). The plastic interaction criteria are presented, in a first step, for some particular combinations of the internal forces, such as axial loading with bending about a main axis, and biaxial bending without axial loading. In these cases, they are given by exact equations (within the frame of the hypotheses adopted in this study). All these plastic interaction criteria are compared with the corresponding plastic criteria adopted in the Eurocode 3 (EC3). Afterwards, a simplified global criterion is proposed for the simultaneous combination of an axial force and bending moments about both the main axes of inertia. This new simplified plastic criterion and the corresponding plastic criterion adopted in the EC3 are compared with the exact solution, obtained by a mixed numerical and analytical integration procedure. This comparison shows that this simplified criterion usually leads to results closer to the exact solutions. Some suggestions are then presented to improve the results given by the EC3. [Copyright &y& Elsevier]

Post-tension hollow core slabs are not common as load receiving floors. While hollowing out the solid slab is to reduce weight as the centre portion of the hollow slab panels carries small self stress. The paper presents an experimental study on the effect of post-tensioned on the ultimate strength of hollow slabs. In this research two units of full scale slab of equal span, cross section and depth are tested in laboratory to failure. Specimens were subjected to experimental with and without post-tension at varying post-stressing. The behaviour of both specimens was studied for bending moments and predominantly shears behaviour. These experiments yielded valuable information concerning the effects of post-tension force to the overall behaviour of failure. Load tests were carried out under seminally serviceability limit state of stresses. It is concluded that post-tension can be used to increase the bearing capacity of hollow slabs by up to 15% with the failure mode changes from flexural to shear as observed in laboratory experiments. [ABSTRACT FROM AUTHOR]

The residual stresses introduced into a component as a result of the mechanical processes necessary for its manufacture significantly influence the fatigue behaviour. The application of loads themselves can, however, alter the initial residual stress distribution, so it is feasible to believe that the residual stress field of a fatigue-stressed structure develops over its entire lifespan. The aim of this article is to analyse the development that the residual stresses initially present in a welded butt joint undergo following the application of an external cyclic load. Comparisons between two residual stress measurements, conducted on the same joint before and after the application of fatigue cycles, have made it possible to obtain interesting information regarding the development of residual stresses in components subjected to fatigue. In particular, it has been found that unlike what is commonly reported, there are particular conditions where the application of a cyclic load results in an increase in the residual stresses initially present, rather than their relaxation. This phenomenon should be taken into consideration in order to avoid unexpected failure in components subjected to fatigue. [ABSTRACT FROM PUBLISHER]